The present invention relates to an occupant position sensor using pattern recognition techniques and methods and arrangements for controlling a vehicular component based on an occupant""s position as determined utilizing pattern recognition techniques.
Crash sensors for determining that a vehicle is in a crash of sufficient magnitude as to require the deployment of an inflatable restraint system, or airbag, are either mounted in a portion of the front of the vehicle which has crushed by the time that sensor triggering is required, the crush zone, or elsewhere such as the passenger compartment, the non-crush zone. Regardless of where sensors are mounted there will always be crashes where the sensor triggers late and the occupant has moved to a position near to the airbag deployment cover. In such cases, the occupant may be seriously injured or even killed by the deployment of the airbag. This invention is largely concerned with preventing such injuries and deaths by preventing late airbag deployments.
In a Society of Automotive Engineers (SAE) paper by Mertz, Driscoll, Lenox, Nyquist and Weber titled xe2x80x9cResponse of Animals Exposed to Deployment of Various Passenger Inflatable Restraint System Concepts for a Variety of Collision Severities and Animal Positionsxe2x80x9d SAE 826074, 1982, the authors show that an occupant can be killed or seriously injured by the airbag deployment if he or she is located out of position near or against the airbag when deployment is initiated. These conclusions were again reached in a more recent paper by Lau, Horsch, Viano and Andrzejak titled xe2x80x9cMechanism of Injury From Airbag Deployment Loadsxe2x80x9d, published in Accident Analysis and Prevention, Vol. 25, No. 1, 1993, Pergamon Press, New York, where the authors conclude that xe2x80x9cEven an inflator with inadequate gas output to protect a properly seated occupant had sufficient energy to induce severe injuries in a surrogate in contact with the inflating module.xe2x80x9d These papers highlight the importance of preventing deployment of an airbag when an occupant is out of position and in close proximity to the airbag module.
The Ball-in-Tube crush zone sensor, such as described in U.S. Pat. Nos. 4,974,350; 4,198,864; 4,284,863; 4,329,549; 4,573,706 and 4,900,880 to D. S. Breed, has achieved the widest use while other technologies, including magnetically damped sensors such as described in U.S. Pat. No. 4.933,515 to Behr et al. and crush switch sensors such as described in U.S. Pat. No. 4,995,639 to D. S. Breed. are also available. Other sensors based on spring-mass technologies are also being used in the crush zone. Crush zone mounted sensors, in order to function properly, must be located in the crush zone at the required trigger time during a crash or they can trigger late. One example of this was disclosed in a Society of Automotive Engineers (SAE) Paper by D. S. Breed and V. Castelli titled xe2x80x9cTrends in Sensing Frontal Impactsxe2x80x9d, SAE 890750, 1989, and further in U.S. Pat. No. 4,900,880. In impacts with soft objects, the crush of a vehicle can be significantly less than for impacts with barriers, for example. In such cases, even at moderate velocity changes where an airbag might be of help in mitigating injuries, the crush zone mounted sensor might not actually be in the crush zone at the time that sensor triggering is required for timely airbag deployment, and as- a result can trigger late when the occupant is already resting against the airbag module.
One trend in the industry was the implementation of Single Point Sensors (SPS) which are typically located in the passenger compartment. In theory, these sensors use sophisticated computer algorithms to determine that a particular crash is sufficiently severe as to require the deployment of an airbag. In another SAE paper by Breed, Sanders and Castelli titled xe2x80x9cA Critique of Single Point Sensingxe2x80x9d, SAE 920124, 1992, which is included herein by reference, the authors demonstrate that there is insufficient information in the non-crush zone of the vehicle to permit a decision to be made to deploy an airbag in time for many crashes. Thus, sensors mounted in the passenger compartment or other non-crush zone locations, will also trigger the deployment of the airbag late on many crashes.
A crash sensor is necessarily a predictive device. In order to inflate the airbag in time, the inflation must be started before the full severity of the crash has developed. All predictive devices are subject to error, so that sometimes the airbag will be inflated when it is not needed and at other times it will not be inflated when it could have prevented injury. The accuracy of any predictive device can improve significantly when a longer time is available to gather and process the data. One purpose of the occupant position sensor is to make possible this additional time in those cases where the occupant is farther from the steering wheel when the crash begins and/or where, due to seat belt use or otherwise, the occupant is moving toward the steering wheel more slowly. In these cases, the decision on whether to deploy the airbag can be deferred and a more precise determination made of whether deployment of the airbag is needed and the characteristics of such deployment.
The discussions of timely airbag deployment above are mostly based on the seating position of the average male (the so called 50% male) relative to the airbag or steering wheel. For the 50% male, the sensor triggering requirement has been typically calculated based on an allowable motion of the occupant of 5 inches before the airbag is fully inflated. Airbags typically require about 30 milliseconds of time to achieve full inflation and, therefore, the sensor must trigger inflation of the airbag 30 milliseconds before the occupant has moved forward 5 inches. The 50% male, however, is actually the 70% person and therefore about 70% of the population sit on average closer to the airbag than the 50% male and thus are exposed to a greater risk of interacting with the deploying airbag. One informal survey, for example, found that although the average male driver sits about 12 inches from the steering wheel, about 2% of the population of drivers sit closer than 6 inches from the steering wheel and 10% sit closer than 9 inches. Also, about 1% of drivers sit at about 24 inches and about 16% at least 18 inches from the steering wheel. The sensor or airbag systems on the market in 1992 did not take account of this variation in occupant seating position and yet this can have a critical effect on the sensor required maximum triggering time.
For example, if a fully inflated airbag is about 7 inches thick, measured from front to back, then any driver who is seated closer than 7 inches will necessarily interact with the deploying airbag and the airbag probably should not be deployed at all. For one analyzed 30 mph barrier crash of a mid-sized car, the sensor required triggering time, in order to allow the airbag to inflate fully before the driver becomes closer than 7 inches from the steering heel, results in a maximum sensing time of 8 milliseconds for an occupant initially positioned 9 inches from the airbag, 25 milliseconds at 12 inches, 45 milliseconds at 18 inches and 57 milliseconds for the occupant who is initially positioned at 24 inches from the airbag. Thus for the same crash, the sensor required triggering time varies from a no trigger to 57 milliseconds, depending on the initial position of the occupant. A single sensor triggering time criterion that fails to take this into account, therefore, will cause injuries to small people or deny the protection of the airbag to larger people. A very significant improvement to the performance of an airbag system will necessarily result from taking the occupant position into account as described herein.
A further complication results from the fact that a greater number of occupants are now wearing seatbelts which tends to prevent many of these occupants from getting too close to the airbag. Thus, just knowing the initial position of the occupant is insufficient and either the position must be continuously monitored or the seatbelt use must be known. Also, the occupant may have fallen asleep or be unconscious prior to the crash and be resting against the steering wheel. Some sensor systems have been proposed that double integrate the acceleration pulse in the passenger compartment and determine the displacement of the occupant based on the calculated displacement of an unrestrained occupant seated at the mid seating position. This sensor system then prevents the deployment of the airbag if, by this calculation, the occupant is too close to the airbag. This calculation can be greatly in error for the different seating positions discussed above and also for the seatbelted occupant, and thus an occupant who wears a seatbelt could be denied the added protection of the airbag in a severe crash.
As the number of vehicles which are equipped with airbags is now rapidly increasing, the incidence of late deployments is also increasing. It has been estimated that out of approximately 400 airbag related complaints to the National Highway Traffic Safety Administration (NHSA) through 1991, for example, about 5% to 10% involved burns and injuries which were due to late airbag deployments. There are also now many known fatalities where a late airbag deployment is suspected as the cause.
The need for an occupant position sensor has been observed by others and several methods have been disclosed in U.S. patents for determining the position and velocity of an occupant of a motor vehicle. Each of these systems, however, has significant limitations. In White et al., U.S. Pat. No. 5,071,160, for example, a single acoustic sensor and detector is disclosed and illustrated mounted lower than the steering wheel. White et al. correctly perceive that such a sensor could be defeated, and the airbag falsely deployed, by an occupant adjusting the control knobs on the radio and thus they suggest the use of a plurality of such transmitter/receivers. If a driver of a vehicle is seated one foot from the transmitter/receiver, and using 1128 feet per second as the velocity of sound, it would require approximately 2 milliseconds for the sound to travel to the occupant and return. The use of the same device to both transmit and detect the sound waves requires that the device cannot send and receive simultaneously and therefore it requires at least 2 milliseconds to obtain a single observation of the occupant""s position. Naturally, as the distance from the occupant to the sensor increases, the observation rate further decreases. For a passenger sitting two feet from the sensor, the delay is approximately 4 milliseconds. Sensors of this type can be used to accurately obtain the initial position of the occupant but the determination of the occupant""s velocity, and thus the prediction of when he/she is likely to be too close to the deploying airbag, will necessarily be inaccurate due to the long delay between position points and thus the small number of such points available for the prediction and the inherent noise in the reflected signal.
Also, ultrasonic transducers send out a pulse that typically is about 0.2 milliseconds long but, due to transducer ringing, this pulse can extend to one millisecond. Furthermore, reflections continue to return to the transducer for up to 6 to 10 milliseconds. Thus, updates from a single ranging transducer can only take place every 6 to 10 milliseconds.
Mattes et al., in U.S. Pat. No. 5,118,134, disclose a single ultrasonic transmitter and a separate receiver, but, no description is provided as to the manner in which this combination is used. In conventional ultrasonic distance measuring systems, the transmitter emits a burst of ultrasonic waves and then measures the time required for the waves to bounce off the object and reach the receptor. The transmitter does not transmit again until the waves have been received by the receiver. This system again suffers from the time delay of at least 6 to 10 milliseconds described above.
Doppler techniques can be used to determine the velocity of the occupant as disclosed below. Both White et al. and Mattes et al., however, specifically state that the occupant""s velocity is determined from a succession of position measurements. The use of the Doppler effect is described in U.S. Pat. No. 3,275,975 to King, but only to determine that the occupant is not moving. No attempt is made by King to measure the velocity of the occupant toward an airbag using this effect. Also none of the references above disclose the use of an ultrasonic transmitter and receiver to simultaneously determine the position and velocity of the occupant using a combination of the transmission time and the Doppler effect as disclosed below.
The object of an occupant position sensor is to determine the location of the head and/or chest of the vehicle occupant relative to the airbag since it is the impact of either the head or chest with the deploying airbag which can result in serious injuries. For the purposes herein, therefore, whenever the position of the occupant is referenced it will mean the position of the head or chest of the occupant and not that of his/her arms, hands or legs. The preferred mounting locations of the transducers, therefore, are those locations which have the clearest unimpeded view of the occupant""s head and chest. These locations are generally at the top of the dashboard, the windshield, the headliner and the rear view mirror. Both White et al. and Mattes et al. disclose only lower mounting locations of the ultrasonic transmitters such as on the dashboard or below the steeling wheel. Both such mounting locations are particularly prone to detection errors due to positioning of the occupant""s hands, arms and legs. This would require at least three, and preferably more, such sensors and detectors and an appropriate logic circuitry for the case where the driver""s arms are the closest objects to two of the sensors. When an unimpeded view is not possible, some means of pattern recognition, which is not disclosed in the above references, is required to differentiate between the occupant and his/her extremities such as his/her hands, arms or legs.
Mattes et al. further describe the placement of the sensor in the headrest but such an arrangement is insufficient since it measures the distance from the headrest to the occupant and not from the airbag.
White et al. further describes the use of error correction circuitry to differentiate between the velocity of one of the occupant""s hands as in the case where he/she is adjusting the knob on the radio and the remainder of the occupant. Three ultrasonic sensors of the type disclosed by White et al. would accomplish this differentiation if two of them indicated that the occupant was not moving while the third was indicating that he or she was. Such a combination, however, would not differentiate between an occupant with both hands and arms in the path of the ultrasonic transmitter at such a location that it was blocking a substantial view of the occupant""s head or chest. Since the sizes and driving positions of occupants are extremely varied, pattern recognition systems are required when a clear view of the occupant, unimpeded by his/her extremities, newspapers. etc., cannot be guaranteed.
As noted above, occupant sensors could assure that the safe proximity to the airbag is maintained. Most such sensors deactivate the airbag if an occupant is in a danger zone. There are several types of occupant sensors that have been proposed and/or are in use (although not necessarily prior to the effective date of the subject matter of most if not all of the claimed inventions), some of which are discussed above. Infrared occupant detection observes the distance where the emitted infrared beams are broken and can determine proximity to the airbag of the occupant from this data. Ultrasonic sensors use sonar-like technology to record echoes and compare them to the sound pattern of the car""s interior. This information can be used to deactivate the airbag if a person is too close to the airbag. Capacitive reflective occupant sensing computes distance by detecting dielectric constant of water within the operating range of the sensor, and can distinguish a human from an inanimate object in the seat. Another capacitive sensor uses a comparison to the dielectric constant of air. A human who is 80 times more conductive than air will register as being in a seat and the distance recognized. Objects not so conductive will not register. A non-register is interpreted as an unoccupied seat. This unoccupied seat message could be used to prevent the airbag from deploying. Force sensing resistors located in the seats can also be used to detect the presence of an occupant. Occupant sensors deactivate airbags if a seat registers as unoccupied or if the occupant is detected too close to the airbag.
The use of a capacitive sensor in a vehicle to generate an output signal indicative of the presence of an object is described in U.S. Pat. No. 6,020,812 to Thompson et al. The presence of the object effects the reflected electric field causing a change in an output signal. The sensor is mounted on the steering wheel assembly for driver position detection or on the instrument panel near the passenger air bag module for passenger position detection. Thompson et al. also describes the use of a second capacitive sensor which generates an electric field which may or may not overlap the electric field generated by the first capacitive sensor. The positioning of the second capacitive sensor determines whether its electric field overlaps. The second capacitive sensor is used to determine whether the occupant is in a normal seating position and based on this determination, affect the decision to activate a safety restraint.
A capacitive sensor may be considered an electromagnetic wave sensor.
Modified occupant sensors have been developed to detect the presence of a child seat. These are fairly simple since only positive detection is required. The fact that a child seat is manufactured under safety regulations makes a permanently mounted sensor feasible. One system has a resonator is built into the child seat and a low power signal from the car prompts a return signal from the resonator sensing the presence of the seat and automatically turning off the passenger""s front airbag. One version of this technology uses a Radio Frequency Identification (RFID) tag. Another sensor uses a normally closed magnetic proximity switch to detect the presence of a child seat. A metal plate installed on the child seat is detected and the sensor deactivates the airbag. These sensors work by detecting the presence of a child (or infant) seat and deactivating the airbag on the front passenger""s side.
Pattern recognition systems for the occupant as used here means any system which will differentiate between the occupant (his or her head and chest) and his extremities (hands and arms) based on relative size, position or shape. Pattern recognition systems can also be used to differentiate an occupant from a seat or a bag of groceries also based on relative size, position or shape or even on passive infrared radiation, as described below.
The occupant position sensor of this invention is adapted for installation in the passenger compartment of an automotive vehicle equipped with a passenger passive protective device (also referred to herein as an occupant restraint device) such as an inflatable airbag. When the vehicle is subjected to a crash of sufficient magnitude as to require deployment of the passive protective device (airbag), and the crash sensor system has determined that the device is to be deployed, the occupant position sensor and associated electronic circuitry determines the position of the vehicle occupant relative to the airbag and disables deployment of the airbag if the occupant is positioned so that he/she is likely to be injured by the deploying airbag. The position of the occupant could be continuously or periodically determined and stored in memory so that instead of determining the position of the occupant(s) after the sensor system determines that the airbag is to be deployed, the most recently stored position is used when the crash sensor has determined that deployment of the airbag is necessary. In other words, the determination of the position of the occupant could precede (or even occur simultaneous with) the determination that the deployment of airbag is desired. Naturally, as discussed below, the addition of an occupant position sensor onto a vehicle leads to other possibilities such as the monitoring of the driver""s behavior which can be used to warn a driver if he or she is falling asleep, or to stop the vehicle if the driver loses the capacity to control the vehicle. In fact, the motion of the occupant provides valuable data to an appropriate pattern recognition system to differentiate an animate from an inanimate occupying item.
According to one embodiment of the invention, an ultrasonic generator transmits a burst of ultrasonic waves which travel to the occupant and are reflected back to a receptor, which may be the same device as the generator. The time period required for the waves to travel from the generator and return is used to determine the position of the occupant and the frequency shift of the waves can be used to determine the velocity of the occupant relative to the airbag.
In another embodiment, infrared or other electromagnetic radiation is directed toward the occupant and lenses are used to focus images of the occupant onto arrays of charge coupled devices (CCD). Outputs from the CCD arrays, are analyzed by appropriate logic circuitry, to determine the position and velocity of the occupant""s head and chest.
In yet another embodiment, a beam of radiation is moved back and forth across the occupant illuminating various portions of the occupant and with appropriate algorithms the position of the occupant in the seat is accurately determined.
In a simple implementation, other information such as seat position and/or seatback position can be used with a buckle switch and/or seatbelt payout sensor to estimate the position of the occupant.
It is a principal object of this invention to provide an occupant position sensor which reliably permits, and in a timely manner, a determination to be made that he/she is out of position, or will become out of position, and likely to be injured by a deploying airbag.
It is also a principal object of this invention to provide a system which could accurately discriminate between the occupant""s head or chest and other parts of the body in determining the occupant""s position and velocity.
It is another object of this invention to independently prevent the deployment of the driver or passenger airbags if either occupant is out of position.
It is still another object of this invention to provide for a more complete analysis of an occupant through the use of receiver arrays, e.g., CCD""s or CMOS arrays, to capture more of the occupant""s image.
Another object of this invention is to provide a warning to a driver if he/she is falling asleep.
Still another object of this invention is to sense that a driver is inebriated or otherwise suffering from a reduced capacity to operate a motor vehicle and to take appropriate action.
Yet another object of this invention is to provide a simplified system for determining the approximate location of a vehicle occupant and to use this system to control the deployment of the passive restraint. This occupant position determining system can be based on the position of the vehicle seat, the position of the seat back, the state of the seatbelt buckle switch, a seatbelt payout sensor or a combination of these.
In order to achieve one or more of these objects, an arrangement in a vehicle for identifying an occupying item comprises means for obtaining information or data about the occupying item and a pattern recognition system for receiving the information or data about the occupying item and analyzing the information or data about the occupying item with respect to size, position, shape and/or motion to determine what the occupying item is whereby a distinction can be made as to whether the occupying item is human or an inanimate object. The analysis with respect to size includes analysis with respect to changes in size, the analysis with respect to shape includes analysis with respect to changes in shape and the analysis with respect to position includes analysis with respect to changes in position. The means for obtaining information or data may comprise one or more receiver arrays (CCD""s or CMOS arrays) which convert light, including infrared and ultraviolet radiation, into electrical signals such that the information or data about the occupying item is in the form of one or more electrical signals representative of an image of the occupying item. If two receiver arrays are used, they could be mounted one on each side of a steering wheel of the vehicle. In the alternative, the means for obtaining information or data may comprise a single axis phase array antenna such that the information or data about the occupying item is in the form of an electrical signal representative of an image of the occupying item. A scanning radar beam and/or an array of light beams would also be preferably provided.
The arrangement could include means for obtaining information or data about the position and/or motion of the occupying item and a pattern recognition system for receiving the information or data about the position and/or motion of the occupying item and analyzing the information or data to determine what the occupying item is whereby a distinction can be made as to whether the occupying item is an occupant or an inanimate object based on its position and/or motion.
An arrangement for controlling a vehicular component, e.g., an airbag, in accordance with the invention comprises means for obtaining information or data about an occupying item of a seat, a pattern recognition system for receiving the information or data about the occupying item and analyzing the information or data with respect to size, position, shape and/or motion, and control means for controlling the vehicular component based on the analysis of the information or data with respect to the size, position, shape and/or motion by the pattern recognition system. The control means may be arranged to enable suppression of deployment of the airbag.
A method for identifying an occupying item of a vehicle comprises the steps of obtaining information or data about the occupying item, providing the information or data about the occupying item to a pattern recognition system, and determining what the occupying item is by analyzing the information or data about the occupying item with respect to size, position, shape and/or motion in the pattern recognition system whereby the pattern recognition system differentiates a human occupant from inanimate objects.
Another method for identifying an occupying item of a vehicle comprises the steps of obtaining information or data about the position and/or motion of the occupying item, providing the information or data about the position of the occupying item to a pattern recognition system, and determining what the occupying item is by analyzing the information or data about the position of the occupying item in the pattern recognition system whereby the pattern recognition system differentiates a human occupant from inanimate objects.
A method for controlling a vehicular component comprises the steps of obtaining information or data about an occupying item of a seat of the vehicle, providing the information or data about the occupying item to a pattern recognition system, analyzing the information or data about the occupying item with respect to size, position, shape and/or motion in the pattern recognition system, and controlling the vehicular component based on the analysis of the information or data about the occupying item by the pattern recognition system. If the vehicular component is an airbag, then control thereof may entail enabling suppression of deployment of the airbag.
Another method for controlling a vehicular component comprises the steps of obtaining information or data about the position of an occupying item of a seat of the vehicle, providing the information or data to a pattern recognition system, analyzing the information or data about the position of the occupying item in the pattern recognition system, and controlling the vehicular component based on the analysis of the information or data about the position of the occupying item by the pattern recognition system.
The disclosure herein also encompasses a method of disabling an airbag system for a seating position within a motor vehicle. The method comprises the steps of providing to a roof above the seating position one or more electromagnetic wave occupant sensors, detecting presence or absence of an occupant of the seating position using the one or more electromagnetic wave occupant sensors, disabling the airbag system if the seating position is unoccupied, detecting proximity of an occupant to the airbag door if the seating position is occupied and disabling the airbag system if the occupant is closer to the airbag door than a predetermined distance. The airbag deployment parameters, e.g., inflation rate and time of deployment, may be modified to adjust inflation of the airbag according to proximity of the occupant to the airbag door. The presence or absence of the occupant can be detected using pattern recognition techniques to process the waves received by the one or more electromagnetic wave-occupant sensors.
Also disclosed herein is an apparatus for disabling an airbag system for a seating position within a motor vehicle. The apparatus preferably comprises one or more electromagnetic wave occupant sensors proximate a roof above the seating position, means for detecting presence or absence of an occupant of the seating position using the electromagnetic wave occupant sensor(s), means for disabling the airbag system if the seating position is unoccupied, means for detecting proximity of an occupant to the airbag door if the seating position is occupied and means for disabling the airbag system if the occupant is closer to the airbag door than a predetermined distance. Also, means for modifying airbag deployment parameters to adjust inflation of the airbag according to proximity of the occupant to the airbag door may be provided and may constitute a sensor algorithm resident in a crash sensor and diagnostic circuitry. The means for detecting presence or absence of the occupant may comprise a processor utilizing pattern recognition techniques to process the waves received by the one or more electromagnetic wave-occupant sensors.
Also disclosed herein is a motor vehicle airbag system for inflation and deployment of an airbag in front of a passenger in a motor vehicle during a collision. The airbag system comprises an airbag, inflation means connected to the airbag for inflating the same with a gas, passenger sensor means mounted adjacent to the interior roof of the vehicle for continuously sensing the position of a passenger with respect to the passenger compartment and for generating electrical output indicative of the position of the passenger and microprocessor means electrically connected to the passenger sensor means and to the inflation means. The microprocessor means compares and performs an analysis of the electrical output from the passenger sensor means and activates the inflation means to inflate and deploy the airbag when the analysis indicates that the vehicle is involved in a collision and that deployment of the airbag would likely reduce a risk of serious injury to the passenger which would exist absent deployment of the airbag and likely would not present an increased risk of injury to the passenger resulting from deployment of the airbag. In certain embodiments, the passenger sensor means is a means particularly sensitive to the position of the head of the passenger. The microprocessor means may include memory means for storing the positions of the passenger over some interval of time. The passenger sensor means may comprise an array of passenger proximity sensor means for sensing distance from a passenger to each of the passenger proximity sensor means. In this case, the microprocessor means includes means for determining passenger position by determining each of these distances and means for triangulation analysis of the distances from the passenger to each passenger proximity sensor means to determine the position of the passenger.
Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.